If you find Fire to be more enjoyable, then I would suggest you just stick with it. Really your DPS isn't at all important unless you are raiding in heroics or with a guild who's struggling with progression in general.
Your DPS is also low because you're not properly used to the spec yet.
As Cassey said, it is far to soon for you to spec fire instead of frost, if your main goal is to be doing optimal DPS.
As of today, fire mages do not compare to frost mages in terms of dps until you aquire a minimun of 45% crit. In addition to this, you should also have the 4-set bonus from Normal raids (at least) before you can expect fire to do as much, or more dps than frost. You should expect to reach this point at around 560 ilvl.
In other words, fire mage is not viable in terms of dps until you start raiding SoO in HC mode.